About those errors displayed in 1.126:
It seems that TW changed a lot, one thing they did was deleting unused materials - and since they absolutely love mess - in particles2.brf there is a lot models like meeting scene terrains, plants etc.
And this brf had ground stones model that used materials that was deleted from materials.brf....
Nevermind.
To fix this bug - just download this:
Place it in\Modules\Polished_Landscapes\Resource (and overwrite file).